English

Cuboids are canonically Ramsey

Combinatorics 2026-03-30 v2

Abstract

We say a set of points CRnC\subset \mathbb{R}^n is canonically Ramsey if there is some set of points SRnS\subset \mathbb{R}^{n'} such that any colouring of SS, with any number of colours, admits either a monochromatic or rainbow copy of CC -- that is to say, some set of points congruent to CC either all receive the same colour, or all receive different colours. Mao, Ozeki, and Wang introduced this notion, proving that 30-60-90 triangles are canonically Ramsey, since when various other canonically Ramsey configurations have been identified (by Geh\'er, Sagdeev, and T\'oth, and others). Fang, Ge, Shu, Xu, Xu, and Yang showed that all triangles and rectangles are canonically Ramsey, and asked whether all cuboids are canonically Ramsey. Here cuboids are sets of the form {0,b1}××{0,bs}\{0,b_1\}\times\dots\times\{0,b_s\}, and in particular may have dimension greater than three. We resolve this question, proving that all cuboids are canonically Ramsey.

Keywords

Cite

@article{arxiv.2603.02189,
  title  = {Cuboids are canonically Ramsey},
  author = {Benedict Randall Shaw},
  journal= {arXiv preprint arXiv:2603.02189},
  year   = {2026}
}

Comments

8 pages; added affiliation and email address

R2 v1 2026-07-01T10:59:44.282Z